The present invention relates to a nipple for nursing bottles.
A conventional nipple for nursing bottles which is now in wide use is formed of a soft material (natural rubber, plastic or the like) shaped like a mother's nipple, with a milk sucking hole formed in the front end of the nipple (see, for example, Japanese Patent Publication No. 38265/1976 and Japanese Utility Model Publication No. 27462/1982).
Such conventional nipple for nursing bottles having a milk sucking hole formed in the front end thereof enables a baby to suck milk from the nursing bottle by simply sucking at the front end portion of the nipple. On the other hand, in sucking mother's milk directly from his mother, a baby puts not only the mother's nipple but also the areola in his mouth and, while moving his upper and lower jaws for mastication, uses his tongue tip to apply pressure to an area extending from the areola to the nipple to squeeze the area for drawing milk. That is, in the case where a mother suckles her baby, the baby could not sufficiently draw milk liquid (mother's milk) by simply sucking at the front end portion of the mother's nipple (the nipple tip).
Recently, the value of feeding a baby on mother's milk has been appreciated anew; however, for some days immediately after childbirth, the breast yields no milk and hence artificial milk is given to the baby through a nursing bottle. And also in other cases where mother's milk is insufficient in amount, reliance has to be placed on artificial milk. In such cases, giving a baby milk through a nursing bottle does not involve so much need for the complicated combined movement comprising masticatory movement of the upper and lower jaws and squeezing movement of the tongue tip as does suckling a baby. For this reason, the baby tends to stop making efforts to suck, and it has been pointed out that this tendency is liable to prevent smooth shift to breast-feeding. And it is also reported that forcing babies to practice said complicated combined movement comprising masticatory and squeezing movements naturally contributes to sound development of the cerebrum.